Sheet metal piercing



M. 19, 1946. A. E. HUTT' 3 M 7 SHEET METAL PIERCING Filed April 13, 1945 2 Sheets-Sheet 1 j za & g l x: l 1

JNVENTOR.

A. E. HUTT' 239mm SHEET METAL PIERCING Filed April 13, 1945 2 Sheets-Sheet 2 Patented Feb. 19, 1946 v 4 2,395,123 H a ,SHEET METAL rmncmo Albert E. nun, Stamford, Oonn.,.asslgnor to Schick Incorporated, Stamford, Conm, a corporation of Delaware Application April 13, 1945 Serial No. 588,153 13 Claims. .(Cl. 164-95) This invention relates to the piercing of holes in sheet metal and has for its primary object the elimination of the need for piercing tools which, as is well known, are extremely costly. both to makeand to maintain, especially'when of the form commonly. requiredfor simultaneously piercing a multiplicity of small holes. While by no means limited thereto, the piercing die problem has been notable in the manufacture of electric shaver shear plates in which many closely spaced apertures have been required to be pierced, the apertures being of a width. say, of .012 of an inch and the sheet metal stock of the same thick- I ness or less.

In its more general aspects the present invention is predicated upon the discovery that highly satisfactory piercing can be effected by'the application of sufdcient liquid pressure to one face of a sheet of metal while rigidly sustaining the opposite face of the sheet except in the precise simultaneously but rather the tendency is for areas to be pierced; in other words, while supporting the sheet on what constitutes a female 'die member recessed or apertured in the exact pattern to be pierced, the usual male or piercing die being entirely dispensed with.

The invention is described belowin greater detail and for purposes of illustration the accompanying drawings show, somewhat diagrammatically. a general form of apparatus appropriate for carrying out the method.

In the drawings, Fi 1 is a vertical section of a form of press suitable for the purpose, Fig. 2 is a similar view, broken out and on an enlarged scale, illustrating the working parts in a different position, and Fig. 3 is abroken out, sectional view of a modification.

Referring to Fig. l a piece of sheet metal I which is to be pierced is located on a suitable rigid support 2 which is recessed or provided with apertures accurately shaped and located to define on the lower surface of the sheet the precise areas of it :to be pierced. The number and shape of the openings will, of course, depend upon the nature of the article to be fabricated but for present purposes can be assumed to consist of six closely spaced, alined, circular holes ofequal size. Accordingly, the support 2, which comprises essentially a female die block,'is provided with six ruptured,without the use of any male piercing die. Preferably, and as below described, a single body of liquid is put under-pressure and utilized to rupture all or a substantial number of the required holes. F

It has also been found that where a plurality of holes is to be pierced by this method, there is no certainty that they will all break through the unsupported areas of the plate to yield at different times and accordingly means is provided to insure that the breaking through of one hole in the plate will not result in such loss of pressure as to interfere with the breaking through of the other holes. In the illustrated structure such means comprises a series of rods or vplungers 4 mounted within. and closely fitting the respective holes 3. At their upper ends the plungers are,

substantially flush with the upper surface of the die block 2 and they are yieldably supported, as by means of a piston member 5 supported by, a spring 8. The piston member 5 is mounted with freedom for limited vertical movement in a cavity 1 in a base block 8 to which the die member 2 is shown secured as by screws 9. y

As the result of. this construction it is of no consequence in what sequence or grouping the unsupported areas of the plate happen to yield.

because each rupture or opening as it occurs will merely lead through theplate to a substantially closed cavity beneath it. This is illustrated in Fig. 2 in which the plate I is indicated as having been ruptured at three of the required six areas, designated l0. As will be understood, the slugs of metal II removed from the holes i0 simply force the rods 4 and plunger member 5 downwardly until the latter seats 'on' the stop I! and ,upon continued application of liquid pressure to appropriately spaced openings 3, shown as extend- I ing clear through the block from top to bottom.

The plate to be pierced is thus rigidly sustained except throughout the areas to be pierced; and it has been found that by the application of sufiicient liquid pressure to the upper surface or the plate, the unsupported areas of it are cleanly the upper surface of the plate the'rem'aining holes are pierced.

The particular apparatus by which liquid pressure is applied to the upper surface of the plate to be pierced may, of course, vary widely but for purposes of illustration a form of all-hydraulic press is indicated. r

, In general, the press comprises a cylinderl3 closed at its upper end by a head ll and secured by bolts l5 to the base 8. Ailiquid, such as oil. is arranged to be supplied under pressure to the upper end of the cylinder through ducts I5, I! and I8 from a master cylinder [9 in which operates a ram 20. A blow-off or safety valve is indicated generally at 2|, the function of which-is simply to relieve the .pressure in the event it should tend to exceed that for which the system is designed.

Within the cylinder I3 is a large piston 22 which is normally maintained in and is returned to the by the line 46 in Fig. 1. Also, as will be understood, the cylinder 29, the upper end of cylinder I3, passages I6, I1 and I8 and cylinder l9 are all filled with the same liquid.

The operation of the press will be understood from the foregoing and need be but briefly described. When pressure is first applied to the upper end of piston 22 by ram 20 the whole piston starts to move downwardly and with it the valve 35. In due course the pressure member 24 engages the upper surface of the sheet to be pierced but shortly prior to such engagement piston 22 will have drawn away from valve 35 with the result that the pressure of the ram is then also applied through hole 34 to the top of piston head 3 I. The pressure thus applied to piston head 3| moves it and plunger 30 downwardly relatively to the piston 22 compressing and generating the sheet-rupturing pressure in cylinder 29 and cavity 21. The position of the parts at this time is indicated in Fig. 2. After the various holes have been pierced the pressure on ram 26 is relieved and the parts are restored to their previous position by their respective springs, the upwardstroke of plunger 36 recharging cylinder 29 ready for the next operation. The return or upward movement of rods 4 serves to eject the slugs I I.

- In Figs 1 and 2 vent passages 4| and 42 are indicated which serve, of course, as escape passages for any liquid which may be forced past the piston head 3I into the space above insert 26.

75 of the Similarly. grooves 43 formed in piston member I and a drain passage 44, as shown in Fig. 2, provide for the escape of any liquid which may be forced past the rods 3 into the cavity I. Also, valve 35 upper limit position shown in Fig. 1 by means of is provided with a lateral vent opening 45 by springs 23 The piston 22 incorporates an openwhich the valve is balanced so far as ram pressure ended, liquid-containing cavity or chamber overis concerned. lying a zone of the sheet I including the unsup- In the course of time'a slight amount of wear ported areas and adapted to be closed by the sheet may occur at the upper ends of the apertures 3 in when the piston is forced downwardly by the die block 2, that is to say. the corners of these liquid pressure applied to its upper end by ram 20. apertures tend to become slightly rounded, but it To his end a pressurev member 24 protruding will be apparent that the die block may be readily slightly from the lower end of piston 22 is secured restored by simply grinding off a small amount by screws 25 to'a shouldered insert 26 which i set ofits upper face' until .it is again entirel fiat into the piston and the lowe'rfsurface of the pres- 16 throughout. sure member 24 is dished, as at 21. The cavity It has been found that while the perforating or thus formed communicates through a passage 26 piercing of the sheet achieved by the above-dewith a central hole 29 in the insert 26. The hole scribed method results in quite clean holes, the 29 constitutes a pressure cylinder in which is entrances to suchholes, that is, o th uppe1- ur mounted a plunger 30, the upper end of the go faceof the sheet, exhibit a very slight bevel or plunger being secured to an auxiliary piston head rounding of the edges of the holes. In many i 3|. Plunger 36 and piston head 3| are biased upst nces this is not only unobjectionable but quite" wardly by spring 32, their upward movement being desirable. In any event, it can be controlled by a limited by a stop plate 33 set into the top of piston modified form of pressure member such as is il- 22. A central opening 34 in the stop plate 33 5 lustrated in Fig. 3 of the drawings. Instead of serves to conduct the pressure liquid to the upper being dished on its lower surface as above-deend of piston head 3| as permitted by a valve genscribed, this pressure member, designated 46, is erally designated 35. dished on its upper surface where it communicates Valve 35 depends from cylinder head I4 and is with the passage 28 and the cavity or depression movable relatively to the head. When piston 22 3 41 thus formed communicates with the lower exis in its upper position, as shown in Fig. 1, valve posed face of the pressure member b means of a 35 is seated in and obstructs the central opening series of holes 48 of precisely the same size as and 34 in stop plate 33, being biased to this position located to register with the holes or apertures 3 in by a spring 36, but the downward movement perthe die block 2, Thus, when the pressure member mitted to valve 35 is limited by its flange 31. In 5 46 is applied to the sheet I in the manner above the result, when piston 22 is moved downwardly. described the latter is exposed to rupturing presvalve 35 follows the piston for a short distance sure only through the exact areas to be pierced and then reaches its lower limit position and furand in the result the edges of the pierced openings ther downward movement of piston 22 uncovers on the upper surface of the sheet are more sharply t e pper d of Opening 34 in op P ate h s defined. In all other respects the apparatus conis illustrated inFig. 2. templated to be used with this modified form of The lower end of the wall of cylinder l 3 is aperpressure member may be the same a that already tured at intervals, as indicated at 33, and the endescribed. tire press is mounted within a trough 39 which T followin i claimed; is filled with oil or the like to the level indicated 5 1. The method of piercing sheet metal which comprises rigidly sustaining the sheet metal throughout an area of one face thereof surrounding and defining the area to be pierced, and applying liquid pressure to the defined area on the 50 opposite face of the sheet metal in an amount sufficient to rupture the unsustained area.

2. The method of piercing sheet metal which comprises rigidly sustaining the sheet metal throughout an area of one face thereof surrounding and defining several areas to be pierced, ap-

plying liquid pressure to an area of the opposite face of the sheet metal, including the areas to be pierced, in an amount sufiicient to rupture the unsustained, areas, and restricting liquid flow through the areas thereby ruptured.

3. The method of piercing sheet metal which comprises rigidly sustaining the sheet metal throughout an area of one face thereof surrounding and defining the area to be pierced, yieldably sustaining the area so defined, and applying liquid pressure to such area on the opposite face of the sheet metal in an amount suflicient to rupture the yieldably sustained area.

4. In an apparatus of the character described,

the combination of a support for a metal sheet to be pierced, the support having a surface recess defining on one face of a sheet applied thereto an area to be pierced, and means for applying sheet-rupturing liquid pressure to theother face sheet.

5. In an apparatus of the character described,

' the combination of a support for a metal sheet to be pierced, the support having a surface recess defining on one face of a sheet applied thereto an area to be pierced, and means for applying sheet-rupturing liquid pressure to the other face of the sheet throughout an area thereof overlying and greater than said recess-defined area.

6. In an apparatus of the character described, the combination of a support for a metal sheet to be pierced, the support having a surface recess defining on one face of a sheet applied thereto an area to be pierced, a yieldable support for such area located in the recess, and means for applying sheet-rupturing liquid pressure to the other face of the sheet..

7. In an apparatus of :the character described, the combination of a support for a metal sheet to be pierced, the support having a surface recess defining on one face of a sheet applied thereto an area to be pierced, means for applying liquid pressure to the other face of the sheet to rupture the same throughout said area, and pressure-maintaining means associated with said recess.

8. In an apparatus of the character described, the combination of a die member having perforations therein defining piercing areas on one face of a sheet applied to the die, a pressure member engageable with the opposite face of such a sheet, said pressure member having a chamber adapted to overlie a zone of such opposite face including the said piercing areas, and means for applying liquid pressure to the chamber.

9. In an apparatus of the character described, the combination of a die member having perforations therein defining piercing areas on one face of a sheet applied to the die, a pressure member engageable with the opposite face of such a sheet, said pressure member having a series of perforations adapted to register with thesaid piercing areas on such opposite face or the sheet, and means for-applying liquid pressure to said series of perforations in the pressure member.

10. In an apparatus of the character described, the combination of a die member having perforations therein defining piercing areas on one face of a sheet applied to the die, a pressure member engageable with the opposite face of such a sheet, means for applying liquid pressure to such 0pposite face of the sheet through said pressure member, a plunger located in each of said perforations and. means for yieldably sustaining the plungers.

11. Sheet-metal piercing apparatus comprising a bed formin a support for a metal sheet to be pierced, the surface Of the bed having an aperture serving to deprive of support the area of the sheet to be pierced, a cylinder mounted on the bed, a piston movaible in the cylinder into engagement with the sheet to clamp the same against the bed, said piston incorporating a liquid-containing cylinder terminating in a cavity overlying the unsupported area of the sheet and adapted to be closed by the sheet whenthe piston is in engagement therewith, and a piston member operable in said liquid-containing cylinder to apply sheet-rupturing pressure-to the liquid and thereby to the sheet.

12. Sheet-metal piercing apparatu comprising a bed forming a support for a metal sheet to be pierced, the surface of the bed having an aperture servin to deprive of support the area of the sheet tobe pierced, a member movable to clamp the sheet to the bed, a liquid-containing cavity overlying the unsupported area of the sheet and means for applying sheet-rupturing pressure to the liquid in said cavity.

13. In an apparatus of the character described, the combination of a support having apertures therein defining areas to be pierced in a sheet applied to such support, yielding means for supporting such areas, means for limiting the yield of the last-mentioned means, and means for applying sheet-rupturing liquid pressure to such areas on the opposite face of the sheet.

ALBERT E HUTI'. 

